Island of Wings, By Karin Altenberg

From Chinua Achebe to Peter Carey and beyond, the ambiguous character of the missionary – committed to spreading Christianity and education, but often a self-deceiving dupe – has recurred in the fiction of empire and its aftermath. As well as preaching the word of God in jungle or outback, these servants of the church (and state) also sought to civilise their own storm-lashed backyards.

In her powerfully imagined debut, Karin Altenberg has delivered a post-colonial novel set not in Africa, Asia or Australia, but at the edge of the British Isles.

The three rocky islands of St Kilda, west of the Hebrides, were inhabited by a stubborn community that wrested a living out of their abundant seabirds – gannets, fulmars, puffins – from prehistoric times until 1930. The final evacuation inspired one of Douglas Dunn's finest poems, "St Kilda's Parliament". Altenberg goes back a century before that, to 1830. St Kilda's new minister, Neil MacKenzie (a historical figure), arrives with his wife, Lizzie, armed with the gospel and dreams of progress for these local versions of the noble savage.

Island of Wings pairs a portrait of a marriage under the extreme stress of social isolation, emotional distance and the death of infant children with a chronicle of the clash between the enlightened faith of the Church of Scotland and the rooted traditions of a Gaelic-speaking pagan place. "The minister did not seem to understand that the ancestors were part of the land," reflects a sceptical island boy – not in the bush, but the United Kingdom itself.

Alongside the struggles of Neil's "spectacular" mission, two other elements lend Island of Wings its rugged grace. First is the evocation of the terrain and its birdlife: not daintily poetic, but as bracing as this landscape needs. Second, Altenberg charts the tempests in Lizzie's mind. Wifely devotion and intermittent joy war with loneliness, longing, the toll of bereavement and an agonising sense of waste. "Is this the man for whom I left everything?" she asks as Neil sinks into distress, even despair.

Their 13-year ordeal lifts the couple into the realm of wind-buffeted tragedy. Romantic and Enlightenment ideals blow in to change forever these remote cliffs and crags – though an editor should have spotted that, in 1831, conversation would have turned not on the abolition of the slave trade (in 1807) but slavery in the Empire itself.